The invention relates to a circuit for generating a triangular voltage across a capacitor, comprising a charging current source for charging the capacitor, a discharging current source for thereafter discharging the capacitor, a comparison stage for comparing the generated voltage with a first and a second reference voltage, respectively, and for respectively generating a setting signal when the value of the first reference voltage is reached, and a resetting signal when the value of the second reference voltage is reached, and a bistable switching element which, in response to the setting or resetting signal, respectively, repeatedly changes its state to control a switch which determines charging or discharging, respectively, of the capacitor.
Such a circuit is disclosed in U.S. Pat. No. 3,745,367. In that prior circuit the bistable element ensures that the capacitor is discharged without fail after the generated triangular voltage has reached the value of one reference voltage, and is charged without fail after the voltage has reached the other reference voltage. The bistable element is formed of transistors with associated resistors, these transistors being operative as controlled switches which are supplied with the supply voltage of the circuit. This implies that these transistors handle comparatively high voltages, that is to say, expressed more accurately, that the voltages at the various electrodes thereof are submitted to a great variation at the transition from one stable state to the other stable state of the element. The same holds for the switch which determines whether the capacitor is charged or discharged, as the case may be.